A Glossary of Water Wheel Terms
Apron- Arc of stone or wooden placed behind a pitch back or beast shot water wheel to prevent water from spilling from the buckets of the water wheel before arriving at the lowest point of the fall. Arms or spokes- extending from the main shaft of a water wheel, that in turn support the shrouding or rims of the wheel, or spokes of a large gear wheel.
Back water or watering- is a condition when the stream rises during a flood and the bottom of the water wheel becomes covered in water. This is a greater problem with overshot water wheels than other types because the water exits the wheel. With the overshot water wheel, water and sometimes air becomes trapped inside the buckets when the water is suppose to exit the buckets and retards it turning motion. Breast shot water wheel- a water wheel powered by a head of water striking the wheel at the point from one-third to two-thirds the height of the wheel, causing the wheel to revolve in a direction opposite to that of the flow of the water in the sluice way or mill race. Buckets- the blades or enclosures formed by blades, around the rim of a water wheel, against which or into the water flows. They called floats or paddles when they are a single flat blade or surface. They generally called elbow buckets or buckets if they are formed from a front plate or blade and a bottom plate or bucket. The back of the bucket or enclosure is created by the soling or drum boards. Bucket water wheel- a water wheel using an enclosed bucket, rather than a simple blade or float, to harness the water power.
Cant- a segment of one of the rings which form the rim of a water wheel or wooden gear wheel. In a water wheel the cant is the piece that has the mortise cut into it to hold the ends of the water wheel float or bucket. Chute- a short trough of wood or iron which conveys the water from the gate to the buckets of a water wheel. It is generally three feet long. Clasp arm water wheel- is a timber wheel built up on a circular frame consisting of two pairs of parallel spokes enclosing the axle at right angles. Compass arm water wheel- is a timber wheel with radiating spokes, mortises to the axle. The arms pass through the shaft and are interlocked together to provide more strength in the water wheel when it is turning.
Drum boards- see sole.
Elbow bucket- the bent or 90 degree water wheel bucket. The elbow bucket or buckets they are formed from a front plate or blade and a bottom plate or bucket. The back of the bucket or enclosure is created by the soling or drum boards. Felloe- A curved board that acts as a face place, that covers up the bolt heads of the layers of boards behind it.
Floating or boat mill- a large diameter undershot water wheel with its gears and machinery inside of a boat and the outboard bearing mounted on pontoon. Also known as an Hungarian Mill. Fore bay- a deep receptacle at the end of a mill race, which water is led into the water wheel or turbine. A reservior or extension of a sluice or mill race. It is where water is passed to the water wheel. Flutter water wheel- is a small diameter water wheel that makes a fluttering sound when operating at a high speed to create a fast stroke or motion.
Greek mill- a simple, early form of horizontal mill, in which a horizontal water wheel with spoon shaped blades is attached to the millstone spindle and drives the runner millstone directly, without requiring any form of gearing. Gudgeon- a metal journal mounted in the end of the main shaft to run in bearings mainly on a water wheel but gudgeons take on other shapes and forms mounted into small shafts either horizontal or vertical. The gudgeon is a round metal shaft which from the side projects 4 (generally in the case of water wheel shafts) wings. The wings fit into slots cut in the end of the water wheel shaft and the remaining end of the journal rides in the bearing. Guide plates- these are metal plates attached to the front side of the water wheel gate control opening. They direct the water into the buckets and often change its direction of flow downward. They are often found on pitch-back, high, middle and low breast shot water wheels. The guide plates are often installed in a series of three plates in a single gate opening.
High breast shot water wheel- a high breast shot water wheel is one in which the water fills or strikes the buckets above the axle of the water wheel shaft. A high breast shot water wheel has elbow buckets. Horizontal water wheel- a water mill whose wheel revolves in a horizontal plane but whose main power shaft is vertical in the mill. Also see Greek mill, and Norse mill. Hungarian Mill- see Floating Mill. Hub- an iron flange that either slides over a wooden water wheel shaft or is mounted onto an iron shaft. Hubs mounted on a wooden water wheel shaft is wedged in place. Hybrid water wheel-an iron hub that simply slides over the wooden shaft and there was no need to cut arm slot holes through the shaft that would cause rot and decay inside of the shaft. The next stage was the replacement of the wooden shaft with an iron shaft that had iron hubs onto which a conventional wooden water wheel was bolted to the iron hubs. Then later wooden elbow buckets and drum boards were built on an all of the metal work of the water wheels is of steel construction. This would mean metal hubs, shaft, arms and bucket shrouds or rim boards.
Iron bands- several iron hoops that are slid over the end of the water wheel shaft that help hold the gudgeon in place.
Low breast shot water wheel- a low breast shot water wheel is one in which the water fills or strikes the buckets below the water wheel shaft. The low breast shot water wheels had deeper buckets to deal with the increased volume of water required for the low head of water to develop power equivalent to that obtained by a high breast shot water wheel.
Middle or mid beast shot water wheel- a middle breast shot water wheel is one in which the water fills or strikes the buckets at the water wheels axle or shaft. The middle breast shot water wheels had deeper buckets to deal with the increased volume of water required for the low head of water to develop power equivalent to that obtained by a high breast shot water wheel.
Noria water wheels- are huge wooden water wheels, known as norias, which once scooped water from the river and deposited it into the aqueducts, which then supplied homes, public buildings and farms. The are a form of undershot water wheel and clay pots are attached to the rim of the water wheels. These wheels are about 20 meters (90 feet) in diameter and still turn today, although their water is not used. The are mainly located in the town of Hama, in Syria. Norse mill- a horizontal mill similar to the Greek mill, but with straight inclined blades to facilitate the removal of ice in winter. The wheel is attached to the millstone spindle and drives the runner millstone directly, without requiring any form of gearing.
Overshot water wheel- a water wheel powered by a head of water striking the wheel just behind its vertical center or just forward of its vertical center of its highest point of rotation. Thus causing the water wheel to revolve in the same direction as the flow of water in the sluice box or sluice way.
Poncelet water wheel- an improved type of under shot water wheel, fitted with curved metal floats invented by General J.V. Poncelet.
Rim plate or shroud plate- the outer covering of the sandwiched sections of the felloe, cant and shroud boards. A piece of either wooden or metal plate molding that cover the outer edges to protect the wood and its layers from damage by water and ice. This covering is either screwed down or bolted down tight against the circumference of both rims of the water wheel. This covering also keeps the front bucket board in place.
Sagebien water wheel- a high volume slow rotating water wheel. The elbow buckets go to the full depth of the water wheel shaft. Built by A. SAGEBIEN (1807-1892) a hydraulics engineer, it was classified as a historical monument in 1987. His water wheel is located at the Trilbardou plant on a Paris canal. In the pump room is the giant water-wheel (11 meters in diameter, 6 meters wide). Shaft (main shaft, water wheel shaft, mill shaft or king pin)- The wooden shaft made of white oak. It is often made from the trunk of a single tree that holds the water wheel. Shock- a phenomenon will develop if water is directed upon the water wheel not in the direction the water wheel rotates, which will retard and in many cases stop the water wheel from turning especially in water wheels that are out of balance. Shroud (shrouding) or rim boards- the rim of a water wheel, which forms the sides of the bucket enclosures. Sole (soling)- the inner lining of a water wheel, forming bottom of the bucket. Also called drum board, sole boards. Starts- the short arms or spurs or arms projecting from the rim of a water wheel, to which the floats or paddles are fastened. Suspension Water Wheel- A hybrid water wheel that is constructed with a combination of wood and metal that is mounted on a hub with metal rods that act as the arms of the water wheel. This is similar to that of a bicycle wheel.
Tide water wheel- a type of water wheel powered by the tidal flow. Tub water wheel- a horizontal water wheel mounted in a tub, constructed of wooden blades, the water enters from a tube or chute, at an angle striking the wheel, which then rotates in a horizontal plane.
Undershot water wheel- a water wheel powered by a head of water striking the wheel at the point near the bottom of the wheel, causing the wheel to revolve in the direction opposite to that of the flow of water in the sluice box or mill race.
Ventilating buckets- a water wheel buckets designed with holes or vents to ease the flow of water and to release trapped air. In wooden wheel are round holes with leather flaps that open to ease entry and to release air as the wheel turns. The most common type of water wheel found on is the breast wheel. Vertical water mill- a traditional water powered mill, driven by a vertical water wheel. Vertical water wheel- a mill with a vertical mounted water wheel on a horizontally mounted axle. The undershot, breast shot and over shot are the forms of this type of water wheel.
Water box- a wooden or metal box at the end of a sluice box or water pipe where the water may regain its height, even out the flow, and where the gate is for the wheel. The water leaves the box by a chute onto the wheel. The classic water box is flound on the Fitz Water Wheels. Water rights- the right to use thewater from a stream to operate a mill. Usually obtained by agreement witha landowner througharbiration by court and state approval. Water house or wheel pit- the area of the mill which the main gearing is located and where the water wheel or turbine(s) may be. Water mill- a mill building whose machinery is fitted to operate using water as its power source. Water power- the power of falling water capable of driving machinery, the water rights possessed by a mill to use water power to perform machanical work. Water wheel- a water powered wheel used by weight and percussion upon a vertical or horizontal wheel used to perform mechanical work, in a place called a water mill. Wedges- are found on a water wheel that hold the gudgeon in place and they hold the water wheel arms also in place. Wooden water wheel- a traditional wooden water wheel is made out of seasoned white oak.
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